POLYMER COMPOSITION FOR FILMS HAVING IMPROVED MECHANICAL PROPERTIES AND DEGRADABILITY

Abstract

Polymeric composition comprising, with respect to the total composition: i) 30-95% by weight, preferably between 50-85% by weight with respect to the sum of components i)-vi), of at least one polyester comprising: a) a dicarboxylic component comprising, with respect to the total of the dicarboxylic component: a1) 30-70% by moles of units deriving from at least one aromatic dicarboxylic acid; a2) 70-30% by moles of units deriving from at least one saturated aliphatic dicarboxylic acid; a3) 0-5% by moles of units deriving from at least one unsaturated aliphatic dicarboxylic acid; b) a diol component comprising, with respect to the total diol component: b1) 95-100% by moles of units deriving from at least one saturated aliphatic diol; b2) 0-5% by moles of units deriving from at least one unsaturated aliphatic diol; ii) 0.1-50% by weight with respect to the sum of components i)-vi), of at least one polymer of natural origin; iii) 0.1-10% by weight with respect to the sum of components i)-vi) of at least one polyhydroxy alkanoate different from a lactic acid polyester referred to in point iv); iv) 0-3% by weight with respect to the sum of components i)-vi) of at least one lactic acid polyester; v) 0-1% by weight, preferably 0-0.5% by weight, with respect to the sum of the components i)-vi) of at least one cross-linking agent and/or a chain extender and/or hydrolytic stabilizer comprising at least one compound di- and/or polyfunctional containing isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline, epoxide, anhydride, diviniether groups and mixtures of these; vi) 0-15% by weight, with respect to the sum of components i)-vi), of at least one inorganic filling agent.

Claims

1) A polymer composition comprising, with respect to the total composition: i) 50-85% by weight, with respect to the sum of components i)-iv), of at least one polyester comprising: a) a dicarboxylic component comprising, with respect to the total dicarboxylic component: a1) 30-70% by moles of units derived from at least one aromatic dicarboxylic acid; a2) 70-30% by moles of units derived from at least one saturated aliphatic dicarboxylic acid; and a3) 0-5% by moles of units derived from at least one unsaturated aliphatic dicarboxylic acid; b) a diol component comprising, with respect to the total diol component: b1) 95-100% by moles of units derived from at least one saturated aliphatic diol; and b2) 0-5% by moles of units derived from at least one unsaturated aliphatic diol; ii) 0.1-50% by weight, with respect to the sum of components i)-vi), of at least one polymer of natural origin, iii) 0.1-10% by weight, with respect to the sum of the components i)-vi), of at least one polyhydroxyalkanoate other than a polyester of lactic acid mentioned in point iv); iv) 0-3% by weight, with respect to the sum of components i)-vi), of at least one polyester of lactic acid; v) 0-1% by weight, weight, with respect to the sum of components i)-vi), of at least one cross-linking agent and/or chain extender and/or hydrolytic stabiliser comprising at least one compound having two or multiple functional groups including isocyanate, peroxide, carbodiimide, isocyanurate, oxazoline, epoxide, anhydride and divinylether groups and mixtures thereof, and vi) 0-15% by weight, with respect to the sum of components i)-vi), of at least one inorganic filler.

2) The polymer composition according to claim 1) in which the aromatic dicarboxylic acids (component a1) are selected from aromatic dicarboxylic acids of the phthalic acid type and heterocyclic dicarboxylic aromatic compounds their esters, salts and mixtures.

3) The polymer composition according to claim 2) in which the aromatic dicarboxylic acids comprise: 1 to 99% by moles of terephthalic acid, its esters or salts; 99 to 1% by moles of 2,5-furandicarboxylic acid its esters or salts.

4) The polymer composition according to claim 1) in which the saturated aliphatic dicarboxylic acids (component a2) of aliphatic-aromatic polyesters i) are selected from C2-C24 saturated dicarboxylic acids, their C1-C24 alkyl esters, their salts and mixtures thereof.

5) The polymer composition according to claim 4) in which the saturated aliphatic dicarboxylic acids (component a2) of aliphatic-aromatic polyesters i) are selected from succinic acid, 2-ethylsuccinic acid, glutaric acid, 2-methylglutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecandioic acid, dodecandioic acid, brassylic acid and their C1-C24 alkyl esters and mixtures.

6) The polymer composition according to claim 1) in which the saturated aliphatic diols (components b1) of the aliphatic-aromatic polyesters are selected from 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,4-cyclohexanandimethanol, neopentylglycol, 2-methyl-1,3-propanediol, dianhydrosorbitol, dianhydromannitol, dianhydropyriditol, cyclohexanediol, cyclohexanmethanediol, dialkylene glycols and polyalkylene glycols of molecular weight 100-4000 and mixtures thereof.

7) The polymer composition according to claim 1) in which the saturated aliphatic diols (components b1) of the aliphatic-aromatic polyesters comprise at least 50% in moles of one or more diols selected from 1,2-ethanediol, 1,3-propanediol, and 1,4-butanediol.

8) The polymer composition according to claim 1) in which aliphatic-aromatic polyesters i) are selected from poly(1,4-butylene adipate-co-1,4-butylene terephthalate), poly(1,4-butylene succinate-co-1,4-butylene terephthalate), poly(1,4-butylene sebacate-co-1,4-butylene terephthalate), poly(1,4-butylene azelate-co-1,4-butylene terephthalate), poly(1,4-butylene brassylate-co-1,4-butylene terephthalate), poly(1,4-butylene adipate-co-1,4-butylene sebacate-co-1,4-butylene terephthalate), poly(1,4-butylene undecanoate-co-1,4-butylene terephthalate, poly(1,4-butylene dodecanoate-co-1,4-butylene terephthalate, poly(1,4-butylene azelate-co-1,4-butylene sebacate-co-1,4-butylene terephthalate), poly(1,4-butylene adipate-co-1,4-butylene azelate-co-1,4-butylene terephthalate), poly(1,4-butylene succinato-co-1,4-butylene sebacate-co-1,4-butylene terephthalate), poly(1,4-butylene adipate-co-1,4-butylene succinato-co-1,4-butylene terephthalate), poly(1,4-butylene azelato-co-1,4-butylene succinato-co-1,4-butylene terephthalate) and mixtures thereof.

9) The polymer composition according to claim 1) in which aliphatic-aromatic polyesters i) comprise repetitive units derived from at least one hydroxy acid in quantities between 0 and 49% in moles with respect to the total moles of the dicarboxylic component.

10) The polymer composition according to claim 1) in which polyester i) has a molecular weight ≥20000, a polydispersity index of molecular weights Mw/Mn of between 1.5 and 10, and inherent viscosity greater than 0.3 dl/g measured using an Ubbelohde viscometer for solutions of concentration 0.2 g/dl in CHCl3 at 25° C.

11) The polymer composition according to claim 1) in which the content of polyester terminal acid groups i) is preferably less than 100 meq/kg.

12) The polymer composition according to claim 1) in which component ii), a polymer of natural origin, is selected from starch, chitin, chitosan, alginates, proteins.

13) The polymer composition according to claim 1) in which the polyhydroxyalkanoate is selected from poly-F-caprolactone, polyhydroxybutyrate (PHB), polyhydroxybutyrate-valerate (PHBV), polyhydroxybutyrate propanoate, polyhydroxybutyrate-hexanoate (PHBH), polyhydroxybutyrate-decanoate, polyhydroxybutyrate-dodecanoate, polyhydroxybutyrate-hexadecanoate, polyhydroxybutyrate hexadecanoate, polyhydroxybutyrate-octadecanoate, and poly3-hydroxybutyrate-4-hydroxybutyrate.

14) The polymer composition according to claim 1) in which the polyhydroxyalkanoate is further characterized in that the hydroxybutyrate co-monomer is higher than 95% by moles with respect to the sum of all the co-monomers

15) The polymer composition according to claim 14) in which the polyhydroxyalkanoate is selected from polyhydroxybutyrate (PHB), and polyhydroxybutyrate-valerate (PHBV).

16) The polymer composition according to claim 1) in which the polyester of lactic acid (component iv) is in quantities from 0 to 2.9% by weight with respect to the sum of components i)-vi).

17) The polymer composition according to claim 1) in which the crosslinking agent and/or chain extender is selected from mixtures of compounds having two or multiple functional groups including isocyanate groups with compounds having two or multiple functional groups including epoxy groups.

18) The polymer composition according to claim 1) in which the inorganic filler (component vi) is selected from kaolin, barytes, clay, talc, calcium and magnesium carbonates, iron and lead carbonates, aluminium hydroxide, diatomaceous earth, aluminium sulfate, barium sulfate, silica, mica, titanium dioxide, wollastonite and mixtures thereof.

19) The polymer composition according to claim 1) comprising, in addition to components i)-vi), one or more polymers other than biodegradable and non-biodegradable components i)-iv) of synthetic or natural origin.

20) The polymer composition according to claim 1) comprising, in addition to components i)-vi), plasticisers, UV stabilisers, lubricants, nucleating agents, surfactants, antistatic agents, pigments, flame retardants, compatibility agents, lignin, organic acids, antioxidants, mould-preventing agents, waxes, process aids and polymer components selected preferably from the group consisting of vinyl polymers, diacid-diol polyesters other than the aliphatic-aromatic polyester described above, polyamides, polyurethanes, polyethers, polyureas, polycarbonates.

21) A film comprising a polymer composition according to claim 1.

22) The film according to claim 21 characterised in that it has a thickness of less than 40 μm.

23) The film according to claim 21 characterised in that it has a tensile strength >15 MPa elongation at break >200%, elastic modulus >200 MPa, determined according to standard method ASTM D882 (tensile properties at 23° C. and relative humidity of 55% and Vo=50 mm/min).

24) The film according to claim 21) characterised by tear strength in the machine direction >80 N/mm, tear strength in the transverse direction >150 N/mm (determined according to ASTM D1922 at 23° C. and 55% relative humidity).

25) The film according to claim 21) selected from: film, both mono- and bi-oriented, and multi-layer film with other polymer materials; film for use in the agricultural sector as mulch films; fabric for use in the agricultural sector as an agricultural textile; stretch film for food, for baling in agriculture and for wrapping waste; films for use in the hygiene sector.

26) An article produced with polymer compositions according to claim 1 selected from: bags and liners for organic collection such as the collection of food waste and grass cuttings; bags for fruit and vegetables and shopping bags; composites with gelatinised, destructured and/or complexed starch, natural starch, flours, or other natural, vegetable or inorganic fillers, as filler.

Description

EXAMPLES

Example 1

[0149] Preparation of the Components of the Polymer Mixture According to the Invention

[0150] Component i)

[0151] i-a=Poly(1,4-butylene adipate-co-1,4-butylene terephthalate) (“PBAT”) prepared according to the following method: 7453 g of terephthalic acid, 7388 g of adipic acid, 12033 g of 1,4-butanediol, 4.4 g of glycerine and 3.4 g of an 80% by weight ethanol solution of diisopropyl triethanolamine titanate (Tyzor TE, containing 8.2% by weight of titanium), in a molar diol/dicarboxylic acid (MGR) ratio of 1.40, were loaded into a steel reactor with a geometric capacity of 60 litres, equipped with a mechanical stirring system, a nitrogen inlet, a distillation column, a knockdown system for high boiling distillates and a connection to a high vacuum system. The temperature of the mass was raised gradually to 230° C. over 120 minutes. When 95% of the theoretical water had been distilled, 17.0 g of tetra n-butyl titanate was added (corresponding to 119 ppm of metal with respect to the amount of poly(1,4-butylene adipate-co-1,4-butylene terephthalate) theoretically obtainable by converting all the adipic acid and terephthalic acid fed to the reactor). The reactor temperature was then raised to 235-240° C. and the pressure was gradually reduced to below 2 mbar within 60 minutes. The reaction was allowed to proceed for the time necessary to obtain a poly(1,4-butylene adipate-co-1,4-butylene terephthalate) with an MFR of about 6.5 (g/10 minutes at 190° C. and 2,16 Kg), and then the material was discharged in the form of rods into a water bath and granulated.

[0152] i-b=Poly(1,4-butylene sebacate-co-1,4-butylene terephthalate-co-1,4-butylene furan-2,5-dicarboxylate) (“PBSTF”) prepared according to the following method: 6414 g of terephthalic acid, 2009 g of 2,5-furandicarboxylic acid, 6939 g of sebacic acid, 10820 g of 1,4-butanediol, 3.95 g glycerine and 3.4 g of an 80% by weight ethanol solution of diisopropyl triethanolamine titanate (Tyzor TE, containing 8.2% by weight of titanium) were loaded, in a molar diol/dicarboxylic acid (MGR) ratio of 1.40, into a steel reactor with a geometric capacity of 60 litres, equipped with a mechanical stirring system, a nitrogen inlet, a distillation column, a knockdown system for high boiling distillates and a connection to a high vacuum system. The temperature of the mass was raised gradually to 235° C. over 120 minutes. When 95% of the theoretical water had been distilled, 17.0 g of tetra n-butyl titanate was added (corresponding to 119 ppm metal with respect to the amount of poly (1,4-butylene sebacate-co-1,4-butylene terephthalate-co-1,4-butylene furan-2,5-dicarboxylate) theoretically obtainable by converting all the sebacic acid, 2,5-furandicarboxylic acid and terephthalic acid fed to the reactor). The reactor temperature was then raised to 235-240° C. and the pressure was gradually reduced to below 2 mbar within 60 minutes. The reaction was allowed to proceed for the time necessary to obtain a poly(1,4-butylene sebacate-co-1,4-butylene terephthalate-co-1,4-butylene furan-2,5-dicarboxylate) with an MFR of about 22 (g/10 minutes at 190° C. and 2.16 kg), and then the material was discharged into a water bath in the form of rods and granulated.

[0153] Component ii)

[0154] ii=native maize starch and plasticiser (75.7% by weight native maize starch, 12.3% by weight polyglycerol and 12.0% added water)

[0155] Component iii)

[0156] iii=polyhydroxybutyrate-valerate (“PHBV”) Enmat Y1000P, MFR (190° C. and 2.16 kg)=14.4 g/10 min. It contains 1.6% moles of 3 hydroxyvalerate units.

[0157] Component iv)

[0158] iv=Polylactic acid (“PLA”) Luminy LX175, MFR (190° C. and 2.16 kg)=3.5/10 min.

[0159] Component v)

[0160] v-a=a styrene-glycidylether-methyl methacrylate copolymer with a molecular weight Mw of approximately 14000 and an equivalent weight of epoxy groups of 420 g/eq.

[0161] v-b=HMV-15CA Carbodilite manufactured by Nisshinbo Chemical Inc.

Example 2

[0162] Granule Characterisation, Filming Process and Mechanical Characterisation

[0163] The compositions shown in Table 1 were fed to a twin-screw APV 2030 co-rotating extruder (L/D=40; diameter 30 mm), operating under the following conditions: [0164] rpm: 170 [0165] capacity: 10 kg/h [0166] thermal profile: 30-90-140-150-200×9-170×3° C. [0167] open degassing.

[0168] The granules thus obtained showed the MFR value (190° C.; 2.16 kg) shown in Table 2 according to ISO 1133-1 “Plastics—determination of the melt mass-flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics—Part 1: Standard method”).

[0169] The granules thus obtained were fed to a Ghioldi model bubble film machine with a 40 mm diameter screw and L/D 30 operating at 64 rpm with a 120-140-170×2 thermal profile. The film-forming head with an air gap of 0.9 mm and L/D 12 was set at 155° C. Film forming was carried out with a blowing ratio of 3 and a stretch ratio of 14 in order to obtain a film with a thickness of 20 μm. The film was then subjected to mechanical characterisation (film tensile strength according to ASTM D882 at 23° C., 55% relative humidity −Vo 50 mm/min). Tear strength tests were performed according to ASTM D1922 (at 23° C. and 55% relative humidity).

Example 3

[0170] Film Disintegration Process

[0171] Disintegration under home composting conditions was carried out according to UNI standard 11355 App. A, whereas disintegration in soil was carried out at a temperature of 28±2° C. using a fertile soil and compost according to ISO17556.

[0172] In both cases the degree of disintegration of the films comprising the composition according to the present invention was determined by inserting the 5×5 cm samples in the slides. The slides were placed over a first layer of soil or compost (depending on the test) of about 4 cm and then covered with a second layer of about 2 cm of soil or compost. The slides were periodically observed and photographed to check the degree of disintegration. A degree of disintegration was attributed according to an empirical scale:

TABLE-US-00001 degree of disintegration gd = 0 Film unchanged degree of disintegration gd = 1 Film with very few (1-2) holes-tears, etc. degree of disintegration gd = 2 Film with widespread tears but structure still intact degree of disintegration gd = 3 Film with degraded areas and widespread breaks, loss of structure degree of disintegration gd = 4 Film with very few residues recoverable with difficulty degree of disintegration gd = 5 Film completely disintegrated, no longer visible

Example 4

[0173] Description of Compositions

[0174] Further to what has been described in example 1, different polymer compositions according to the invention and different comparison compositions were prepared.

[0175] Table 1 describes the various compositions that were then fed into the extruder

TABLE-US-00002 TABLE 1 Compositions fed into the extruder Components % i v Compositions i-a i-b ii iii iv v-a v-b Composition 1 71.26 0 24.14 4.01 0 0.15 0.20 Comparative 71.26 0 24.14 0 4.01 0.15 0.20 composition 1 Composition 2 61.26 0 32.01 6.13 0 0.20 0.15 Comparative 61.26 0 32.01 0 6.13 0.20 0.15 composition 2 Composition 3 71.26 0 24.14 3.03 0.98 0.15 0.20 Composition 4 64.26 5 26.14 4.01 0 0.15 0.20

[0176] 0.24% by weight, with respect to the sum of components i)-vi), of a process adjuvant, Atmer SA 1753, was added to all the compositions.

[0177] Table 2 describes the rheological properties of the compositions and the water content of the granules as a percentage by weight based on the total composition after the extrusion process.

TABLE-US-00003 TABLE 2 Properties of the granules obtained MFR (160° C., Final granule 5 kg) water content Compositions (g/10 min) %) Composition 1 5.4 0.6 Comparative composition 1 4.6 0.5 Composition 2 4.9 0.7 Comparative composition 2 4.3 0.6 Composition 3 4.6 0.6 Composition 4 5.2 0.7

Example 5

[0178] Results of Tests on Mechanical Properties

[0179] The different compositions described in example 4 were tested as described in example 2.

[0180] The results are shown in Table 3.

TABLE-US-00004 TABLE 3 Properties of films of thickness of 20 μm with the compositions shown in Table 1 Mechanical properties Tear strength σb εb E (N/mm) Compositions (MPa) (%) (MPa) MD TD Composition 1 38.7 529 259 92 193 Comparative 29.6 439 199 99 104 composition 1 Composition 2 25.4 464 293 191 253 Comparative 25.2 399 298 180 134 composition 2 Composition 3 29.3 543 223 113 210 Composition 4 28.5 417 205 82 74

[0181] As can be seen, the compositions according to the invention not only show a general improvement in mechanical properties, but also have a surprisingly improved effect on the tear strength of the film in the transverse direction.

Example 6

[0182] Film Disintegration Test Results

[0183] The different compositions described in example 4 were tested as described in example 3.

[0184] The results are given in Tables 4 and 5.

TABLE-US-00005 TABLE 4 Disintegration of films including the compositions shown in Table 1 in soil Disintegration in Compositions soil at 182 days Composition 1 gd = 5 Comparative composition 1 gd = 2 Composition 3 gd = 4 Composition 4 gd = 4

TABLE-US-00006 TABLE 5 Disintegration of films including the compositions shown in Table 1 in home composting Compositions Disintegration in home composting Composition 2 gd = 5 at 100 days Comparative gd = 5 at 120 days composition 2

[0185] As can be seen, the compositions according to the invention have a considerable effect on the disintegration kinetics.